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3 13 Objective 2 Normally, the number of electrons in an atom equals the number of protons and the overall charge of the atom is zero. However, atoms may gain or lose ...

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List the 3 main types of ¾ subatomic particles and ...

3 13 Objective 2 Normally, the number of electrons in an atom equals the number of protons and the overall charge of the atom is zero. However, atoms may gain or lose ...

Basic Chemistry Objective # 1
„ Why do we study chemistry in a biology
List the 3 main types of
course? subatomic particles and
¾ All living organisms are composed of indicate the mass and
electrical charge of each.
chemicals. To understand life, we must
understand the structure, function, and 2
properties of the chemicals that make up
living organisms.

1

Objective 1 – Subatomic Particles Objective # 2

Name Symbol Charge Mass Mass Describe the basic structure of the
Proton atom and be able to define the
(daltons) Number following terms: nucleus, energy
level, isotope, and ion.
p +1 1.00728 1
4
Neutron n 0 1.00867 1
Objective 2
Electron e -1 0.00055 0
6
3

Objective 2

„ Atoms are composed mainly of protons,
neutrons, and electrons.

„ The protons and neutrons are closely
packed together in the central part of the
atom called the nucleus

„ The electrons are in constant, random
motion around the nucleus. They are
organized into energy levels or shells located
different distances from the nucleus:

5

Objective 2 Objective 2

„ Energy levels and shells mean the same 8
thing.

„ We use numbers to identify the energy
levels (1, 2, 3, etc) or letters to identify the
shells (K, L, M, etc).

„ Electrons in higher energy levels tend to
have more energy and tend to be located
farther away from the nucleus than
electrons in lower energy levels:

7

Objective 2 Objective 2
„ Rules for filling energy levels:
¾ The first electrons in an atom enter the K „ The pattern for filling higher shells
becomes more complex and will not
shell, up to a maximum of 2. concern us. However, what you
¾ The next electrons enter the L shell, up to should remember is that even though
any shell beyond L can hold more than
a maximum of 8. 8 electrons, it will not hold more than
8 when it is the outermost shell.
9
10
Objective 2
Objective 2
„Atoms that have the same
number of protons but different 12
numbers of neutrons are called
isotopes.

11

Objective 2 Objective 2

„ Normally, the number of electrons in an atom „ The gain of electron(s) is called reduction
equals the number of protons and the overall and the loss of electrons is called oxidation.
charge of the atom is zero.
„ Atoms that have gained or lost electrons
„ However, atoms may gain or lose electrons: and are no longer electrically neutral are
¾ If an atom gains electrons, it will have an extra called ions:
¾positive ions = cations
negative charge for each electron gained. ¾negative ions = anions
¾ If an atom loses electrons, it will have an extra
14
positive charge for each electron lost.
13

Objective 2 Objective # 3

15 Define the term “element” and
know the names and chemical
symbols of the principle
elements found in living
organisms.

16

Objective 3 Objective 3 – Some Important
Elements in Living organisms
„ An element is a substance composed
of only one type of atom. Element Symbol # of protons 18
Oxygen O 8
„ By “one type of atom”, we mean all Carbon C 6
the atoms have the same number of Hydrogen H 1
protons. However, the number of Nitrogen N 7
neutrons and electrons in the atoms Calcium Ca 20
that make up an element can vary. Phosphorus P 15
Potassium K 19
17

Objective # 4 Objective 4

„ Be able to determine the number of „ The number of protons in an atom is
protons, neutrons, and electrons in an called the atomic number. All atoms of the
atom if you know its atomic number, same element ALWAYS have the same
atomic mass, and overall charge. Also be atomic number.
able to determine the number of electrons
in each energy level of an atom if you „ The number of protons plus the number
know the total number of electrons of neutrons in an atom is called the atomic
present. mass or atomic weight. Different isotopes
of the same element will have different
19 atomic weights.

20

Objective 4 Objective # 5

„ # p = atomic number Define the term “molecule” and
„ # n = atomic mass – atomic number explain how the molecular
„ # e: formula (or chemical formula)
¾ If overall charge is 0, #e = #p and the structural formula are
¾ If overall charge is +, take the #p and used to provide information
about a molecule.
subtract one for each overall + charge
¾ If overall charge is -, take the #p and add 22

one for each overall - charge

21

Objective 5 Objective 5

„ Molecule: a unit composed of two or more HO
atoms joined together by chemical bonds. CO

„ Structural formula: shows us the actual H O Structural
arrangement of the atoms.
Formula
„ Molecular formula or chemical formula:
tells us what types of atoms and how many H2CO3 = Chemical formula 24
of each are joined together.

23

Objective # 6 Objective 6

Explain the difference between „ Element: a substance composed of only
an element, a compound, and a one type of atom (all the atoms have the
mixture. same number of protons). The atoms may
occur signally, or they may be joined to
25 form molecules. The smallest unit of an
element that retains the properties of the
element is a single atom. e.g. hydrogen

26

Objective 6 Objective # 7

„ Compound: a substance composed of 2 or Explain how the number of
more elements that have been joined by electrons in the outermost shell
chemical bonds. The smallest unit of a of an atom affects the number
compound that retains the properties of and type of chemical bonds the
the compound is a molecule. e.g. water atom can form.

„ Mixture: a combination of 2 or more 28
substances that do NOT chemically
combine and retain their individual
properties. e.g. sugar mixed with salt

27

Objective 7 Objective 7
„ How can an atom obtain a stable outer
„ Electrons in the outermost shell are called:
valence electrons shell of electrons if it doesn’t already have
one?
„ Atoms join together in ways that give each ¾ Gain electrons
atom a stable outer shell of electrons: ¾ Lose electrons
¾ Share electrons
¾ If the first shell is the outer shell, it is stable
with 2 electrons. 30

¾ If any other shell is the outer shell, it is
stable with 8 electrons.

29

Objective # 8 Objective 8a

„ Discuss the mechanism involved in „ Ionic bonds:
forming the following types of chemical
bonds, describe their characteristics, and ¾ Involve a transfer of electrons from one
be able to give examples of each: atom to another in order to give both atoms
a stable outer shell.
a) Ionic bond
b) Nonpolar covalent bond ¾ The transfer of electrons produces oppositely
c) Polar covalent bond charged ions that attract each other to form
d) Hydrogen bond the ionic bond. e.g. when Na and Cl come
near each other, Na loses an electron and Cl
31 gains it.

32

Objective 8a Objective 8b & 8c

„ Covalent bonds involve a sharing of one or
more pairs of electrons between 2 atoms in
order to give both atoms a stable outer shell.

„ In covalent bonds, electrons are always
shared in pairs:

¾ One pair = single covalent bond
¾ Two pairs = double covalent bond
¾ Three pairs = triple covalent bond

33 34

Objective 8b & 8c Objective 8b & 8c

35 „ Nonpolar covalent bonds involve an equal
sharing of electrons between atoms. Each
atom has an overall charge of zero.

„ Polar covalent bonds involve an unequal

sharing of electrons between atoms. The

atom that attracts the electrons more

strongly has a slight negative charge and

the atom that attracts the electrons more

weakly has a slight positive charge. 36

Objective 8d Objective 8d

„ Hydrogen bond: 38
¾ The weak attraction between a covalently

bound H atom with a slight positive charge
and another covalently bound atom with a
slight negative charge.
¾ May occur between different molecules or
between different parts of the same
molecule.

37


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